THE TENSEGRITY SYSTEM AND PELVIC PAIN SYNDROME

Tensegrity, a new System of mechanics, can be used to model biomechanical systems from viruses to vertebrates. Pelvic mechanics are readily understood using this System. Biomechanical dysfunction can also fit into the tensegrity model. When function, dysfunction and mechanics are combined into the same system we can obtain a more holistic concept of the various pelvic pain syndromes and how to best treat them.

Keywords: Tensegrity, biomechanics, pelvic pain, dynamical disease.

INTRODUCTION

Tensegrity, the mechanical System of bicycle wheels,9 viruses," biologic cells," and many biologic multicellular structures" is gaining scientific and lay acceptance as the "architecture of life". Scientific American, a science news magazine with a worldwide circulation of over 600.000, features an article about `tensegrity'in its cover story in January 1998.'° If we accept the tensegrity concept it will virtually turn biomechanics an its head and require a paradigm shift in thinking. If we ignore tensegrity mechanics we are in peril of interpreting our clinical and experimental observations using an outmoded model. We are in stage of biomechanies much akin to the geocentric vs. heliocentric arguments in Copernicus' time. At the very least, we must test our theories in both Systems and See which fits best, since, like the geocentric and heliocentric theories, tensegrity and classic Newtonian biomechanics are mutually exclusive.

In 1992 and again in 1995 World Congress an Low Back and Pelvic Pain the focus seemed to be the sacroiliac joint, its mechanics and its role in generating pain. There are several references to joint injection as the `gold Standard' for diagnosis and for treatment. This need to stress joint pathology is rooted in the Newtonian concepts that the skeleton and its joints are the frame upon which the soft tissue hang, and the concept that pathology is a function of anatomical disease or injury.

On the other hand, tensegrity stresses that the bones of the skeleton are but compression elements `floating' in a highly structures, self generating, hierarchical, integrated tension network of soft tissues.'3." The ligaments, muscles and fascia take an a whole new importance and joint mechanics becomes soft tissue mechanics. This is consistent with the clinical observations of Mennell,'3 who stressed the play movement of joints as a necessary dynamic function and Trave11` who focused an the imbalance of tension of the muscles and fascia as a source of musculoskeletal pain and dysfunction. These works echoed the pioneering precepts of A.T. Still, Palmen and others who focused an the dynamic aspects of the musculoskeletal System rather than the anatomical pathology of the structures.

DYNAMICAL DISEASE

In 1988 the NY academy of Science, in conjunction with NIH held a conference `Perspectives in Biological Dynamics and Theoretical Medicine' who's theme was `dynamical diseases'. To quote Fraiser "the motion of Systems and not their anatomy frequently defines a disorder." At that conference it was pointed out that `diseases' such as irritable bowel Syndrome, asthma, benign cardiac arrhythmia and the like, are not anatomic pathological processes bat malfunctions of the rhythms of the systems. One of the defining characteristics of a dynamical disease is that, unlike an anatomical pathologic disease, the healing process in nonlinear. Anatomical healing has a prescribed, linear healing process. A cut will go through a recognized and clearly definable process, fibroblastic proliferation, organization etc., That has a proscribed time sequence. Dynamical diseases may suddenly convert and normalize. An asthma attach may suddenly cease and leave hardly a trace. Hives may appear and disappear in seconds. A migraine headache may disappear as quickly as it started. Musculoskeletal impairment that can suddenly revert to normal function alter manipulation, myofascial release or treatment of a trigger point must surely be a dynamical disease, related to the rhythms of the system rather than anatomic pathologic changes. It then may be deceiving to bank an uncovering anatomical pathologic processes in the Joint of myofascial tissues in order to make a clinical diagnosis. This is particularly so since it is recognized that many of these anatomical changes, such as those described in inter vertebral discs, may be no more than incidental findings. As pointed out by Nachemson only 20% of patients with back pair have an anatomically pathologic process as a possible cause of their pair.

Tensegrity

"The evolutionary paradigm is necessary for the scientific study of macro and meta complexity, whereas the Newtonian paradigm is only suitable for the limiting case of microcomplexity". William H. Weekes.

"Continued emphasis an generalities that cannot be transformed into meaningful specifics, as well as the emphasis an specifics that cannot be transformed onto meaningful generalities, cannot be tolerated. " Hans Christian van Baeyer.

Biologic constructs are evolutionary, hierarchical structures, mechanically stable at each instant of development. Each molecule, Organelle, cell, Organ and organism is structurally Sound, independent and also interdependent. Tensegrity is an evolutionary System of micro to macro to meta structural development based an known and accepted laws of physics as it applies to biology. If Standard post and beam Newtonian constructs were used to model biologic structures then biologic tissues would exceed their known capacities. Using known measurements and mathematical calculations based an Newtonian mechanics the human spine would buckle with less than the weight of the head an top of it'6 and the vertebral bodies would crush under the leverage of a fly rod held in the hand. Urinary bladders and pregnant uteri would burst when fall and, with each heartbeat, arteries would lengthen enough to crowd the brain out of the skull. Animals larger than a lion would continually break their bones and dinosaurs larger than an elephant would have crushed carrying their own weight.'° Since biologic structures and organisms perform these tasks with apparent ease it seems logical to look at other models to see if there is a better fit between what is calculated and what is observed. The `tensegrity' model of continuous tension, discontinuous compression, first conceived by Snelson," and named and adapted by Fuller' is a non Newtonian mechanical system that is to be gaining wider acceptance as the bases of the architecture of life.

Figure 1.

(a) Compressing a ring.

(b) A wagon wheel loads by compressing each rung in turn.

(c) A bicycle wheel loads by continuous tension of all the spokes at the same time.

The difference between Newtonian and Hookian post and beam mechanics and the mechanics of tensegrity is the difference between the mechanics of a wagon wheel and a bicycle wheel. In a wagon wheel the load is transferred through the structure by loading of directly connected compression elements. The weight of the wagon presses an the axle which presses an the wheel hub which compresses the underlying spoke which, in turn, compresses the rim of the wheel (fig. 1 b). In bicycle wheel mechanics the weight of the frame transfers to the hub of the wheel which is hung in a tension network of wire spokes (fig. lc). There is continuous tension of the spokes, which are pre stressed, but the compression elementsare discontinuous and do not compress one another. The hub remains suspended in its tension network. Compression loads are distributed around the rim. The compression elements behave in a counterintuitive way, not loading one another as in Newtonian construct but loaded by the tension elements. The rim of the wheel is compressed by the distributed tension of the spokes. The hub hangs from the spokes, which are always under tension, and the spoke under the hub is never compressed. Compress structures unload into the tension network. Rather then the primary support elements of the system as they would be in a pillar of skyscraper Model the compression elements become secondary to the tension support network. Fuller' calls these structures "tensegrity" structures as a contraction of "tension intergrity". Other familiar tensegrity structures are the tennis racket that transmits the compression force of the racket frame to the ball through the strings, snowshoes and the Buckminster Fuller geodesic domes. Tensegrity structures transmit loads through tension and compression only. They are fully triangulated and, therefore, there are no bending moments in these structures and no shear. If the front and rear hubs are linked to each other by the frame we develop a hierarchical system where the load an the bicycle is suspended in a tension network. The frame of a bicycle is suspended from the ground by the network of wire spokes of the two wheels. This works even if we do "wheelees" (rear up an one wheel) and transfer the entire load to one wheel. Tensegrity can be used to model biologic structures from viruses to vertebrates and their systems and subsystems.

We now generally accept that the sacrum hangs from the ilea by its ligaments. A ligamentous tension system for support and stability is consistent with the known anatomy. If we use a cycle wheel-tensegrity structure as our model for the pelvis ring would be the rim and the sacrum would be the "hub" of the pelvis' (fig. 2). The mang tension elements of ligaments and muscles attached to the sacrum stabilize it. The sacrum is suspended as a compression element within the musculo-ligamentous envelope and transfers its loads through that tension network. Even standing an one leg the sacrum would sit within its tension network, just as does the bicycle hub when doing "wheelees". By changing the tension of the muscles or ligaments through their attached muscles as the hamstrings the sacrum could piston or rotate but remain as part of the tensegrity network. This would provide omnidirectional structural stability, independent of gravity, hierarchical, load distributing and allow mobility as well as stability. The rim could distribute its load, rather than local loading. In a compressive loading system with each step the heads of the femurs would smash into the soft concellous bone of the acetabulum. In a tensegrity system the forces generated at the hip would not concentrate in the acetabulum but be efficiently distributed throughout the pelvic bones and soft tissue. The sacrum would remain suspended in its soft tissue envelope and transmit the loads above and the forced below through the pelvic ligaments and muscles.

In the tensegrity-pelvic wheel model the coccyx and lower sacrum takes an new importance. The coccyx no longer can be considered a vestigial Organ but rather the hub of a dynamical structure. The coccyx and pelvic floor in which it floats, are important in upright stance, mechanical stability when Lifting, respiration, ambulation, micturition, defecation, sexual function and parturition. The piriformis, obturator internus and hamstrings muscles are part of the pelvic floor dynamics and important in upright stance, ambulating and lifting. You cannot lift any significant weight without setting your pelvic diaphragm. The coccyx moves with each breath and is integrated into all the pelvic visceral functions.

CLINICAL APPLICATION

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Sacroiliac

Piriformis

Gleuteus Maximus

Gleutus Minimus

Qudratus Lumborum

Tensor Fascia Latae

Pelvic Floor Myalgia

Coccygodynia

Levator Ani

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Table 1.

Myofascial Pelvic Pain Syndromes

The various myofascial low back and pelvic pain syndromes are well described in the orthopedic, osteopathic, physical medicine, proctologic and gynecologic (Table 1). Several articles have recognized the interrelationship of these syndromes and the need for a multidisciplinary approach to diagnose and treat these syndromes. The interrelationship of these conditions and treatment model is best understood when tensegrity is used as the anatomic and dynamic model when evaluating and treating the many seemingly unrelated dynamic pelvic pain syndromes. It seems clear that these are all different aspects of the Same 'dynamical disease' and they should be evaluated and treated as the Same entity. There are many diagnostic tests described of pelvic floor related problems, lumped together as myalgias of the pelvic floor but also including coccyx, sacroiliac, symphysis pubis and even hip mechanics but the sine quo non is the diagnostic rectal and/or vaginal pelvic examinationi. There is a very definable and discrete tender point, usually at the medial end of the sacrospinousligament as it attaches to coccyx and lower sacrum that defines the patients pain. Pace and Nagle," looking for this tender point, state "an examination for low back pain is incomplete unless a rectal or vaginal examination is performed" (italics Pace and Nagle's). Wyant echoes these Sentiments and it is repeated in most of the other literature an this subject. It is my experience that when patients having the various pelvic pain syndromes are examined for this tender point many of these seemingly separate conditions are linked through the pelvic wheel. Unfortunately this requisite examination "is more honored in its breach than in its performance."

Once the condition is defined the treatment seems rather straightforward and simple. Theile described an intra pelvic stretch technique, very similar to trigger point techniques described by Travell and Simons to treat this condition and subsequent authors have confirmed a sixty to eighty percent success rate with these techniques (with the usual modifications by various authors) since its first description in 1936. My experience has been the same. These intra pelvic stretching techniques can be performed rectally or, in females, vaginally. The choice of access depends an the particular structure being treated and therapists and patient choice. Wyant points out that vaginal access is often easier and Travell and Simon" indicate that both vaginal and rectal access might be necessary. Most. authors add stretching and strengthening exercise programs for the piriformis, pelvic floor and associated hip and back muscles. These would make Sense, using the tensegrity model. In a bicycle wheel you cannot adjust one spoke without having to adjust the others. In keeping with the concept ofdynamical diseases, the improvement may often be sudden and dramatic. This is particularly true if it is a sudden, recent condition causing the problem. As time goes an secondary mal adaptations usually occur and need to be treated as well. That would be adjusting the other spokes an the tensegrity wheel. Theile used a series of treatments daily over seven to ten days. Other authors have various modifications of the technique. At my facility the usual course of treatment is three to six treatments over a two-month period with the last few treatments mostly fine-tuning. There are flaw physical therapists an both sides of the Atlantic trained in these specific intra pelvic techniques and appropriate exercises.

Additionally, injections into the various structures may be necessary for recalcitrant lesions or to facilitate the stretching techniques. Injections into the posterior sacroiliac, iliolumbar, sacrospinous and sacrotulerous ligaments, piriformis muscle and coccyx, either singly or in multiples, all have their proponents. I try to be selective and treat only those structures that have specific tender points. Injections can be local anesthetics, various steroids, prolotherapy compounds and other injectables depending an the experience of the practitioner.

CONCLUSION

When looking at musculoskeletal pelvic pain syndromes through newer and now accepted biomechanical and clinical models we can reinterpret what is already known and observed clinically. We can make some scientific sense of what appeared to be a confusing picture of disparate clinical entities. Much of the low back and pelvic pain syndromes appear to be more a function of tissue and structure dynamics rather than anatomic pathologic processes. MRls, x-ray studies, joint contrast injections and the like, are but single frames of a moving picture and tell us little about the dynamics and functional rhythms of the musculoskeletal system. They must be interpreted with caution. Clinical examination using time tested techniques still is the most valuable and accurate method of assessing the dynamics of the musculoskeletal system and the clinician should not be seduced by technology until it provides us with the musculoskeletal equivalent of an echo cardiogram. The tender or trigger points studied by many clinicians over the years cannot be discounted as a valuable tool and must be related to dynamical diseases of the musculoskeletal system. When evaluating a patient with pelvic pain the examination is incomplete without an orthopedic pelvic and/or rectal examination to look for those tender points. These tender points disappear when treatment is adequate and therefore are the hallmark of successful treatment of these conditions. Any clinical study of painful pelvic lesions must include evaluation of these tender points in order to be of value.

25. Theile GH; Tonic spasm of the levator, ani, coccygeus and piriformis muscles: Its relationship to coccygodynia and pain in the region of the hip and down the leg. Trans AM Proct Soc 37: 145-155,1936.

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